This invention relates in general to universal joints for vehicle drive train systems. More specifically, this invention relates to an improved structure for a seal and seal guard assembly adapted for use in such a universal joint.
Universal joints are well known devices which provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joints are widely used between rotatable drive shaft sections in vehicle drive train systems. A typical universal joint includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups to facilitate relatively low friction rotational movement therebetween. The bearing cups which are mounted on a first opposed pair of the trunnions are connected to a first end yoke which, in turn, is secured to an end of a first drive shaft section or other component of the vehicle drive train system. Similarly, the beating cups mounted on a second opposed pair of the trunnions are connected to a second end yoke which, in turn, is secured to an end of a first drive shaft section or other component of the vehicle drive train system.
Typically, each of the trunnions has an internal lubricant passageway formed therein. The lubricant passageways communicate with a central cavity formed in the body of the cross. An external lubricant fitting is mounted in an aperture formed through the body of the cross to provide one-way fluid communication into the central cavity. Thus, lubricant injected into the cross through the fitting flows outwardly from the central cavity through each of the lubricant passageways to the bearing cups mounted on the ends of the trunnions. The lubricant passes around the outer ends of the trunnions and inwardly back between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups. In this manner, the needle bearings can be lubricated for use.
It is known to provide elastomeric seals within or about the open ends of the bearing cups to retain the lubricant in the regions of the universal joint where the needle bearings are located, and further to minimize the entry of dirt, water, or other contaminants therein. Additionally, it is also known to provide rigid guards within or about the open ends of the bearing cups to prevent the entry of dirt, water, or other contaminants into the regions of the universal joint where the needle bearings are located and to protectively cover the elastomeric seals. In some instances, the seals and the guards are combined into a single seal and guard assembly. A number of conventional seals, guards, and seal and guard assemblies are known in the art. However, known structures have been found to be unduly complex and somewhat difficult to assemble. Thus, it would be desirable to provide an improved structure for a seal and guard assembly which is simple and inexpensive in construction and assembly.